A 120 kW Symmetrical Multi-Winding Split Planar Transformer for High-Power High-Efficiency Isolated DC-DC Applications

In this article, a 120 kW symmetrical multiwinding split planar transformer (SMWSPT) based on ferrite cores is proposed for high-power high-efficiency isolated dc–dc applications. A novel multiwinding structure based on the Archimedes spiral is employed, so a symmetrical multiwingding structure is realized. Consequently, the proposed winding structure not only boosts the power rating of the split planar transformers but also provides a good current sharing among the windings. Meanwhile, the proposed multiwinding structure permits the application of distributed compensation capacitors and connects each of the windings to the paralleling converters, avoiding the directly parallel connections of the SiC-mosfets within the power converter and the associated current sharing issues. The operating principles and the analytical model of the proposed SMWSPT are presented and investigated in detail. Finally, a 120 kW SMWSPT prototype is built and tested on a 39 kHz CLLC converter. The peak efficiency of the CLLC converter is about 99.310%, and the efficiency at the full load of 120 kW is about 99.137%. The power density of the proposed SMWSPT is 24.90 kW/L. This article shows for the first time that the split planar transformer can achieve the power up to 120 kW with high efficiency and high-power density.